A combined photon-hadron hodoscope calorimeter

The energy and spatial resolution and other characteristics of a combined detector permitting simultaneous detection of a large number of photons and hadrons has been studied in a 200 GeV/c hadron beam at the CERN SPS. The detector consists of the GAMS-4000 spectrometer (4096 lead-glass cells) and a modular hadron calorimeter MHC-200 located behind it (240 total-absorption sandwich counters). A new method for adding the signals from the two calorimeters, which takes into account the difference in the development of hadron showers in photon and hadron calorimeters, has been developed. It permits substantial improvement of the energy resolution of the combined detector. The hadron coordinates are defined with a precision of several millimeters and the energy resolution is typical for steel-scintillator sandwiches with a wavelength-shifter readout. The effect of the gap between the photon and the hadron calorimeters has also been studied.     

Test of a prototype of the ZEUS backing calorimeter

We have studied the performance of a high resolution uranium-scintillator calorimeter followed by a much coarser backing calorimeter, made out of iron plates interleaved with planes of limited streamer tubes. The test results, obtained at the CERN-SPS hadron beam, show that the backing calorimeter can be used either to veto events with significant energy leakage from the uranium calorimeter or to correct for the energy. In both cases the energy resolution of the combined calorimeters improves significantly compared to the uranium calorimeter alone.     

The xenon olive detector for the next generation colliders

We propose a fast detector with high resolution and fine granularity, consisting of a xenon electromagnetic shower counter and a TMS-uranium hadron calorimeter. Both are linear in energy, insensitive to radiation damage and have good spatial resolution in 3-dimensional space in order to measure di-electron and di-jet masses at the next generation high luminosity colliders.     

A simple model of hadron calorimeters

A simple model of hadron calorimeter response is examined. It is found that not only must a hadron calorimeter be compensated in order to achieve linearity, but also that the intrinsic hadron and electromagnetic resolutions must be equal if the calorimeter resolution is to be independent of energy and have a Gaussian distribution.     

Performance of a BGO calorimeter with photodiode readout and with photomultiplier readout at energies up to 10 GeV

Bismuth germanate (BGO) calorimeter arrays, consisting of up to 12 elements of 30 × 30 × 200 mm³ have been tested at the CERN PS with pions and electrons of up to 10 GeV/c momentum, and at SIN with pions, electrons and protons up to 450 MeV/c. Both photomultiplier (PM) and photodiode (PD) readouts were used. Accurate calibration in the 100 MeV energy range was achieved with stopping protons, stopping pions and minimum ionizing pions. With 212 MeV electrons and PM readout, a time resolution of the BGO signal of 640 ps fwhm has been measured. The energy resolution for electrons above 1 GeV (PD readout) was found to be roughly constant at σ/E ～ 1%. This is consistent with a negligible intrinsic resolution for BGO at these energies, after taking into account shower leakage and PD noise. For electrons of 92 and 200 MeV, we obtained (PM readout) energy resolutions close to the theoretical limit given by photon statistics and shower leakage. The electron/hadron separation was better than 1:500 over the energy range of 0.5 to 10 GeV, and improved to better than 1:1000 after a simple pattern cut. The energy deposition of the e.m. showers, both laterally and longitudinally (rear leakage), was found to be in agreement at the 0.1% level with Monte Carlo calculations using the SLAC-EGS program.     

Hadron cascades induced by electron and photon beams in the GeV energy range

We consider the calculation of high energy hadron cascades induced by electron and photon beams in the GeV energy range. The most important source of high energy hadrons is the hadronic interaction of photons from the primary electron-photon shower. The hadronic interaction of high energy photons is described by the vector meson dominance model and by a Monte Carlo version of the dual multistring fragmentation model. The results of the calculation are compared to experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets. The electron beam induced hadron cascade is calculated in extended materials.     

Performance of a lead glass spectrometer at high energies

The performance of a photon detector consisting of two lead glass arrays and three planes of proportional tubes is reported. The detector was designed to measure the energies and positions of photons in the energy range 3–50 GeV. An energy resolution of $\text{1.0\% +}\text{5.0\%}\text{√E}$ (standard deviation) and a spatial resolution approaching 3 mm (standard deviation) were achieved during calibration with a low intensity positron beam. The energy resolution was degraded during use with a high intensity hadron beam whereas the spatial resolution was only slightly affected.     

Investigations of the characteristics of the DELPHI hadron calorimeter prototype

The characteristics of the DELPHI hadron calorimeter prototype in various modes of operation of its detectors are presented in this paper. It is shown that the transition to a saturated proportional mode and the use of more sensitive electronics do not worsen the hadron calorimeter operation. The possibility to select muon tracks in the hadron calorimeter and to use them for detector triggering has been investigated. The results of nuclear shower simulation in the detector are presented.     

A 5 in. Si(Li)/Pb sampling calorimeter telescope for observation of cosmic gamma rays in the GeV region

A 5 in. diameter Si(Li)/Pb sampling calorimeter with a depth of 28 radiation lengths (30 unit cells × 0.93 radiation lengths) has been constructed. The energy and angular resolutions of the calorimeter have been investigated using CERN SPS positron beams with energies of 10 to 147.8 GeV. The calorimeter shows good linearity over this energy region and the energy resolution is expressed well by σ_E (rms)/E = (16.9 ± 0.9)%/ √E[GeV], where E represents the incident beam energy. The angular resolution of the calorimeter for a single event is 0.3° (rms) at 80 GeV/c. The agreement between these results and Monte Carlo simulations is good.

We are showing a new design of the Si(Li)/Pb sampling calorimeter telescope (SSCT) with an angular resolution (point source localization capability) of about 0.04° (rms) for bright galactic gamma-ray sources. We believe that this telescope is a suitable detector for future observations of cosmic gamma rays in the GeV region, especially when used to search for point sources.     

Some characteristics of plastic streamer tubes

The operating characteristics of plastic streamer tubes chosen as a detector of the DELPHI-LEP hadron calorimeter are described. The work has been performed using a set-up specially designed to investigate a hadron calorimeter prototype on a beam of the Dubna synchrophasotron. The apparatus operated on-line with an ES-1040 computer.     

The segmentation of hadron calorimeters

Optimization of the segmentation of large hadron calorimeters is important in order to obtain good resolution for jet physics at minimum construction cost for the next generation of high energy experiments. The principles of the segmentation of hadron calorimeters are discussed. As an example, the Monte Carlo optimization of the segmentation of the L3 hadron calorimeter barrel at CERN is described. Comparisons of results for the reconstructed jet shapes show that the optimum number ADC channels is about 20K for the readout of 450K wires of the proportional chambers. The matching between the sandwiched φ towers and Z towers is the dominant factor for angular resolution. Based on these Monte Carlo simulations, an optimized tower structure is obtained.     

Results from a CsI(Tl) test calorimeter with photodiode readout between 1 and 20 GeV

Results from a test with a CsI(Tl) calorimeter will be presented. The purpose was to evaluate the use of CsI(Tl) for high resolution electromagnetic calorimetry. A resolution of about 1% has been measured between 4 and 20 GeV. A very high electron/hadron separation of > 1 : 1000 has been observed. Prospects and limitations for large scale applications will be discussed.     

Electron-pion discrimination in an iron/streamer tube calorimeter up to 100 GeV

An electron/hadron calorimeter consisting of 2 cm/4 cm iron sampling planes and streamer tube readout modules was exposed to particle beams of electrons and pions in the energy range from 1 to 100 GeV. At the highest energies the observed pion misidentification amounted to 0.95% ± 0.21% at an electron detection efficiency of 95%.     

Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method ATLAS

This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within ±1% of the true values and the fractional energy resolution is

Full-size image

. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74±0.04 and agrees with the prediction that e/h>1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.     

Detection of single X-ray quanta with a magnetic calorimeter

We give a status report on the development of a particular low temperature calorimeter with new experimental results. On absorption of an X-ray photon the increase of temperature changes the magnetization of a diluted magnetic sample, and this quantity is measured with a SQUID-magnetometer. It is a special feature of this experimental method that the magnetic sample has a very high heat capacity and an additional absorber for a compound detector does not change the sensitivity essentially. Besides a short summary on earlier measurements we present new results with metallic magnetic samples, which give shorter signal rise times (below 100 μs). On a compound detector with 0.1 g of LaB₆:Er and an absorber of 12 g sapphire, the energy resolution for 5.9 keV and 60 keV X-ray sis 1.6 keV and 2.6 keV (FWHM), respectively. With a silicon absorber an energy resolution of 1.4 keV at 5.9 keV has been found. The energy resolution is in any case limited by two effects. On the one hand the signal height is strongly reduced due to an additional heat capacity of the magnetic sample and on the other had we have an additional noise from the conduction electrons of the metallic sample. Possible improvements with respect to both effects are discussed.     

The performance of an L3 hadron calorimeter prototype module with BGO

A prototype of a gas sampling uranium module of the L3 hadron calorimeter was built and subsequently tested with pion beams of energies between 4 and 20 GeV. The construction of the proportional chambers, the assembling of the module, the readout electronics, and the beam test are briefly described. The energy resolution of the calorimeter module alone was measured to be 30.5 ± 3% at 6 GeV, 21 ± 2% at 10 GeV and 18 ± 2% at 20 GeV. For the module together with a BGO crystal matrix in resolution was 29 ± 3% at 4 GeV, 21 ± 2% at 10 GeV, and 17 ± 2% at 20 GeV.     

Performance of the radphi detector and trigger in a high rate tagged photon beam

We describe the design and operation of a detector system for measuring all-photon decays of mesons photoproduced in a tagged photon beam with energies between 4.3 and 5.4 GeV and a flux of 5×10⁷ tagged photons per second. Photons from meson decays were detected with a lead-glass calorimeter with an energy resolution of 11% at 1 GeV. Various veto and trigger components were also present. Final states with as many as six photons were successfully detected and reconstructed.     

A hadron-blind detector

The development of highly efficient solid photocathodes, compatible with high-gain gaseous detectors, has opened the possibility to build threshold Cherenkov counters with a good hadron rejection, with a minimum amount of matter, and a time resolution of the order of the nanosecond. We discuss the properties of a hadron-blind detector, with a granularity of a few millimetres. The study of the background sources shows that a rejection power of the order of 99% can be achieved for high-energy hadrons. It permits instantaneous multi-hadron rejection and, combined to a fast electromagnetic calorimeter, can ensure on-line electron selection, even when they are produced close to hadronic jets. It could permit the operation of lepton-tracking detectors in a magnetic field, in very high hadronic backgrounds.     

Pulse shapes in single photon,single particle calorimeters

Single photon or single particle calorimeters with energy resolutions of order 1 eV fwhm have recently been proposed as detectors for X-ray astronomy and many other applications. Such devices consist, essentially, of an absorber (linked to a heat bath at ∼ 0.1 K) and one or more thermistors The temperature rise induced in the former element by the absorption of a single photon or particle produces voltage waveforms at the ouput of the latter from which energy information may be abstracted. In this paper, we consider the practical limits to the energy resolution which arise from the “thermal nonuniformity” of the absorber mass. The variation in thermistor pulse shape with position of photon absorption is estimated from solutions of the heat conduction equation, for a number of linear calorimeter designs. An assessment is made of the position-sensing properties of a calorimeter with two line-end thermistors.